Supporting information

Zhipeng Chen, Qian Chai, Sen Liao , Yu He, Yu Li, Wenwei Wu, Bin Li

School of Chemistry and Chemical Engineering, GuangxiUniversity,

Nanning530004, Guangxi,China

1. Studythe third stage using the distributed activation energy model (DAEM)

1.1 Theoretical

The distributed activation energy model(DAEM)has been widelyused to analyze kinetics of complex materials[43-45]. The model assumes that a number of parallel, irreversible andfirst-order reactions with different activation energies occur simultaneously.And the difference in activation energiesis represented by a distribution function f(Ea):

(1S)

whereα is the degrees of conversion of decomposition reaction at temperature T,f(Ea) is a distribution curve of the activation energythat represents the difference in the activation energies of the manyfirst-order irreversible reactions.β is the linear heating rate of the decomposition reaction, and A is the pre-exponential factor.

A new simplemethod for estimating f(Ea) and A in the distributed activation energy modelwas presentedby Miura and Maki[45]. f(Ea) and A can be estimated accuratelywith the new method.The equation is expressed as follows:

ln(β/T2) = ln(AR/Ea) + 0.6075- (Ea/R)*(1/T) (2S)

The procedure to estimate f(Ea) and A usingthis method is as follows(The results presented in this paper were calculated by the programs compiled by ourselves):

(1) Measureαvs.T relationships at at least threedifferent heating rates.

(2) Calculate the values of (β/T2)at selected αvalues from the αvs.T relationships obtained fordifferent heating rates.

(3) Plot ln(β/T2)vs.1/T at the selectedαvalues,and determine the Ea and A values from the Arrheniusplots at different α values using the relationship inEq.2S. Both the Ea and A values corresponding to theαvalues can be obtained from the slope and theintercept in each Arrhenius plot.

(4) Plot theαvalue against the obtained activation energy,Ea, and differentiate the αvs Earelationship to obtain f(Ea).

1.2 Results

AccordingtoEq.2S, the Miura-Maki integral method was usedin the calculation (the interval of degrees of conversion,Δα, is 0.02). The DAEM resultsof the third stage of the thermal decomposition of NH4Co0.9Zn0.1PO4·H2Oare obtained and shown in Figures3S-5S.And the average values of Eaand Aof the third stage are determined to be 300.7 kJ mol-1 and 5.36×1017 s-1, respectively.

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2. Tables

Table 1S. The parameters of compensation effect

for thermal decomposition ofNH4Co0.9Zn0.1PO4·H2O

β/ K min-1 / a / b
The first stage
5 / 0.2978 / -2.6760
8 / 0.2942 / -2.3138
10 / 0.2911 / -2.0473
15 / 0.2871 / -1.7189
The second stage
5 / 0.2388 / -3.4461
8 / 0.2359 / -3.0048
10 / 0.2337 / -2.7582
15 / 0.2313 / -2.3810

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Table 2S. Algebraic expressions of functions [g(α) and f(α)]

and corresponding mechanism [28]

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3. Figures

Fig.1SFT-IR spectra of the product (a) and the sample calcined at 923 K (b)

Fig.2SSEM images of the product (a) and its calcined product (b) at 923 K for 3 h

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Fig.3SDependenceofαon Eαobtained from Eq. 2Sfor the third stage of the thermal decomposition of NH4Co0.9Zn0.1PO4·H2O

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Fig.4SDependenceof lnAon Eα obtained from Eq. 2Sfor the third stage of the thermal decomposition of NH4Co0.9Zn0.1PO4·H2O

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Fig.5S f(Eα) curvefor the third stage of the thermal decomposition of NH4Co0.9Zn0.1PO4·H2O

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*Corresponding author. Tel.: +867713233718; Fax: +867713233718

E-mail address: ,,(S. Liao).